Different Cruise controll issue

I've got an '03 Disco 42K on it. The criuse controll is very "jerky". It's always excellerating or letting off. It's almost nauseating . I've taken it do the dealer for service and, they've replaced "The Computer" and "Reprogramed" the cruise control. It's still doing it. Is this a normal thing?

Brian

Since you are in warranty, get it into the dealer and let them play with it, hey, do your 45K while you're in there, hell it's free.
mike

Yeah, I really should. Good plan.

I had an 04, new from the dealer, and it did the same. I took it back to have checked out and it still did the same. I now have an 03 and it too is doing the same. Any Help.
Thanks

I've heard on other posts and fourms that you should take your truck to the dealership and have them switch out the cruise control module from a 4.6 to a 4.0??? I believe thats what I heard... correct me if im wrong..

John-Robert

Check the basics, the vaccum lines are the biggest cause of the cruise not working, especialy the long line that goes to the switch on the brake pedal assembly.
Mike

I have the exact opposite problem on a 2000 Disco II (125K).  The dealer replaced the vacuum hoses, but it still did not work, they said I needed a new ECU.  While waiting for a new ECU to arrive, I tried the Cruise Control and it worked (kind of)  It is very slow to pick up speed, but will eventually get to the set speed.  An example of slow is:  If I am doing 60 mph on a flat road and the CC is set to 70mph, and I "resume" and let gp of the throttle, the car will slow to 50 mph before the CC starts to accelerate it, it will take 40-50 secs before it gets up to 70 mph.
 
I thought originally that it was the vacuum hoses still leaking, but I have checked the ones on the vavcuum pump and control switch and all is okay.
 
I have read the various messages in the forums here that refer to a vacuum hose from the brake pedal to the CC vacuum control switch.  However, the service manual does not mention it, and I cannot find it.
 
Did they change the design between years?
Before I replace the ecu ($300) does anyone have any other ideas.
 
Regards Phil
 

Just my two cents, I have a 2001 disco that the cruise control is jerky also. Just a crappy design?
 
                  Bob

I have the same problem on my '03 SE7, I read somewhere else in the forum that's its a simple dealer reprogram.  They apparently didn't update the cruise control software when swtinching from the 4.0 to the 4.6L.  I think someone said it's about $100 at the dealer.  I planb to get mine done next time I head in.

I had the same problem on my '03 and the dealer just reprogramed - works great now.